Machine body and working machine

ABSTRACT

A machine body including an exhaust after-treatment apparatus that executes a reduction treatment on a predetermined oxide in exhaust gas from an engine using a liquid reducing agent. A reducing agent tank provided at a position distant from the engine stores the liquid reducing agent, and a working fluid tank positioned between the exhaust after-treatment apparatus and the reducing agent tank stores a working fluid having a high temperature at least during operation of the machine. A reducing agent supply line is arranged along the working fluid tank at a position above a level of the fluid stored in the working fluid tank to supply the liquid reducing agent from the reducing agent tank to the exhaust after-treatment apparatus. Accordingly, the liquid reducing agent stored in reducing agent tank is unlikely to be thermally affected by the engine, and the liquid reducing agent flowing through the reducing agent supply line is unlikely to be thermally affected by the fluid stored in the working fluid tank.

TECHNICAL FIELD

The present invention relates to a machine body with an exhaust after-treatment apparatus that executes a reduction treatment on a predetermined oxide in exhaust gas from an engine using a liquid reducing agent, and a working machine provided with the machine body.

BACKGROUND ART

In recent years, in order to deal with the emission control standard Tier 4 Final (Tier 4f), an exhaust after-treatment apparatus that reduces nitrogen oxides in exhaust gas from the engine to clean the exhaust gas has been adopted for working machines, such as a urea Selective Catalytic Reduction (SCR) system.

A urea system has strict temperature restrictions because the system includes components that may deteriorate in durability when the system is exposed to high temperature for a long time, or because reducing action may be affected when a liquid reducing agent in a reducing agent supply line, typically urea, becomes hot. Therefore, the layout of the system needs to be determined such that the components of the system and the urea in the components fall within an allowable temperature range.

Specifically, a urea tank needs to be installed at a location where the tank is not exposed to high temperatures. A urea line connecting the urea tank to an injector also needs to be routed so as to minimize influence of heated components around the urea line.

In this regard, a line routing between a side surface of a hydraulic oil tank or fuel tank and a decorative cover that covers the side surface of the tank is known, for better outer appearance and effective utilization of dead space (for example, Japanese Patent Application Laid-open No. 2006-274675 and Japanese Patent Application Laid-open No. 2011-2506602). However, if the configuration disclosed in the prior art is applied to a urea line, heat from the hydraulic oil or fuel stored in the tank may cause the temperature of the urea system to fall outside the allowable temperature range.

In view of these circumstances, it is an object of the present invention to provide a machine body that can suppress a liquid reducing agent temperature rise and a working machine provided with the machine body.

SUMMARY OF THE INVENTION

An aspect of the present invention is a machine body including an exhaust after-after-treatment apparatus that executes a reduction treatment on a predetermined oxide in exhaust gas from an engine using a liquid reducing agent. A reducing agent tank provided at a position distant from the engine stores the liquid reducing agent, and a working fluid tank positioned between the exhaust after-treatment apparatus and the reducing agent tank stores a working fluid having a high temperature at least during machine operation. A reducing agent supply line is arranged along the tank at a position above a level of the fluid stored in the tank to supply the reducing agent from the reducing agent tank to the exhaust after-treatment apparatus.

According to this aspect, the liquid reducing agent stored in reducing agent tank is unlikely to be thermally affected by the engine, and the liquid reducing agent flowing through the reducing agent supply line is unlikely to be thermally affected by the fluid stored in the tank, which has become a predetermined temperature or higher during operation. Consequently, temperature rise of the liquid reducing agent can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a general perspective view depicting an important part of an embodiment of a machine body according to the present invention, and FIG. 1B is an enlarged perspective view of a part of FIG. 1A;

FIG. 2 is a perspective sectional view of the position of a tank in FIG. 1;

FIG. 3 is a front view depicting a working machine provided with the machine body;

FIG. 4 is a perspective view depicting an important part of another embodiment of the machine body according to the present invention; and

FIG. 5 is a perspective sectional view of the position of a tank in FIG. 4.

DETAILED EMBODIMENT

The present invention will be described below in detail based on an embodiment depicted in FIGS. 1 to 3.

As depicted in FIG. 3, a hydraulic excavator type working machine 10 has a machine body 11 including a lower traveling body 12 and an upper slewing body 13 provided on the lower traveling body 12 so as to be able to slew. A bucket type working apparatus 14 is mounted on the upper slewing body 13 of the machine body 11.

On front portion of the upper slewing body 13, a cab 15 with an operator seat and a storage box 16 for tools and the like are provided on either side of an attachment portion for the working apparatus 14. Also on the upper slewing body 13, working fluid tanks such as a fuel tank 17 and a hydraulic oil tank 18 are provided backward of the storage box 16 side by side in a front-rear direction (adjacent to each other). On the back of a slewing bearing portion of the upper slewing body 13, an engine room 19 and a pump room (not depicted in the drawings) are located side by side in a lateral direction, with a counterweight 20 installed backward of the engine room 19. Therefore, the fuel tank 17 and the hydraulic oil tank 18 are positioned between the storage box 16 and the engine room 19, and the storage box 16 and the engine room 19 are located away from each other.

As depicted in FIG. 1A, FIG. 1B, and FIG. 2 the fuel tank 17 and the hydraulic oil tank 18 are shaped like boxes and contain fuel (not depicted in the drawings) and hydraulic oil O that are fluids. The fuel tank 17 and the hydraulic oil tank 18 are located along a side portion of the upper slewing body 13 (machine body 11). The fuel tank 17 has a side surface portion 17 a is an external side portion facing the side portion of the machine body 11, and the hydraulic oil 18 has a side surface portion 18 a that is an external side portion facing the side portion of the machine body 11. That is, the side surface portion 17 a and the side surface portion 18 a extend in plane along a front-rear direction and an up-down direction and are covered with a decorative 21 defining an external side surface of the machine body 11. The hydraulic oil tank 18 internally has a sufficient air layer so as to prevent the internal pressure of the hydraulic oil tank 18 from being excessively elevated by the hydraulic oil O returning when hydraulic cylinders S1, S2, and S3 used for the working apparatus 14 and serving as fluid pressure actuators are contracted. the level OS of the hydraulic oil O in the hydraulic oil tank 18 is constantly kept below an upper surface portion 18 b, which is an upper end (upper portion) of the hydraulic oil tank 18, by the air layer.

The decorative cover 21 is formed to extend beyond the fuel tank 17 and the hydraulic oil tank 18 in the front-rear direction and the up-down direction. The decorative cover 21 has an inner surface facing but spaced away from the side surface portions 17 a and 18 a. Therefore, there is a space S extending in the front-rear direction and the up-down direction between the decorative cover 21 and both the side surface portion 17 a of the fuel tank 17 and the side surface portion 18 a of the hydraulic oil tank 18.

An engine 22 is installed in the engine room 19. On one side of the engine 22, a cooling fan (not depicted in the drawings) is installed to cool a cooling package (not depicted in the drawings) such as a radiator and an oil cooler by cooling air introduced from outside to the cooling package. On the other side of the engine 22, an exhaust gas cleaning apparatus 23 executes exhaust gas cleaning treatment in an exhaust system of the engine 22.

As seen back in FIG. 3, an engine hood 24 is provided at an upper portion of the engine room 19 so as to be able to be opened and closed. A tip of an exhaust pipe 25 which discharges the exhaust gas from the engine 22 protrudes from the engine hood 24. A side door is provided on an external side surface of the engine room 19 so as to be able to be opened and closed.

As depicted in FIGS. 1 to 3, the exhaust gas cleaning apparatus 23 has a diesel particulate filter 27 to remove particulate matter in the exhaust gas, and a selective catalytic reduction apparatus 28 to execute reduction treatment on a nitrogen oxide that is a predetermined oxide in the exhaust gas, located side by side in the lateral direction. A rear end of the diesel particulate filter 27 is connected to an exhaust port of the engine 22 via a connection pipe (not depicted in the drawings) corresponding to a starting point of the exhaust pipe 25. A rear end of the selective catalytic reduction apparatus 28 is connected to a front end of the diesel particulate filter 27 via a pipe 28 a. The remaining part of the exhaust pipe 25 is connected to a front end of the selective catalytic reduction apparatus 28.

An injector 29 is attached to a pipe 28 a connecting the front end of the diesel particulate filter 27 to the rear end of the selective catalytic reduction apparatus 28, to inject a liquid reducing agent such as urea water into the pipe 28 a.

A reducing agent supply apparatus 31 is provided for the injector 29 in order to supply the liquid reducing agent to the selective catalytic reduction apparatus 28. Reducing agent supply apparatus 31 is positioned away from the engine 22 so as not to be thermally affected by the engine 22.

The reducing agent supply apparatus 31 includes a liquid reducing agent tank 32 preferably installed in the storage box 16, a liquid reducing agent pump 33 that pumps the liquid reducing agent, and a reducing agent line 34 serving as a supply line that extends from the liquid reducing agent pump 33 through the line path in the machine body 11 to the injector 29 in the exhaust gas cleaning apparatus 23.

An upstream end 34 a that is a front end of the reducing agent line 34 is arranged to extend rearward from the liquid reducing agent pump 33 and upward at a position in front of the fuel tank 17. A front intermediate portion 34 b that is a first intermediate portion of the reducing agent line 34 is arranged to extend along the side surface portion 17 a of the fuel tank 17 through the space S between the decorative cover 21 and the side surface portion 17 a of the fuel tank 17 so as to incline gradually upward and rearward, that is, toward the hydraulic oil tank 18. A rear intermediate portion 34 c that is a second intermediate portion of the reducing agent line 34 contiguous with the front intermediate portion 34 b is arranged to extend generally horizontally in the front-rear direction (closer to the decorative cover 21) above an edge of an upper surface portion 18 b of the hydraulic oil tank 18 that is contiguous with the side surface portion 18 a.

A downstream end 34 d of the reducing agent line 34 is arranged to be contiguous with a rear end of the rear intermediate portion 34 c and to extend upward from the back of the hydraulic oil tank 18 and then to bend into the machine body 11 toward the exhaust gas cleaning apparatus 23 along an upper portion of the pump room positioned below the exhaust gas cleaning apparatus 23. The position of the rear intermediate portion 34 c of the reducing agent line 34 is above the level OS of the surface of hydraulic oil O stored in the hydraulic oil tank 18 and is located opposite an inner surface of the decorative cover 21. The reducing agent line 34 is fixed at a plurality of positions on the side surface portion 17 a of the fuel tank 17 and the upper surface portion 18 b of the hydraulic oil tank 18 or on an inner surface of the decorative cover 21 that faces the side surface portion 17 a of the fuel tank 17 and the side surface portion 18 a of the hydraulic oil tank 18, using separate fixtures 35, for example, brackets. The reducing agent line 34 is preferably located spaced above the edge of hydraulic oil tank 18 by the fixtures 35 instead of closely contacting the surface.

FIG. 1B illustrates the front intermediate portion 34 b and the rear intermediate portion 34 c fixed to the fuel tank 17 and the hydraulic oil tank 18, respectively, for clarification of description. A downstream end 34 d of the reducing agent line 34 is fixed to an upper portion of a pump room cover 37 that covers the pump room, using a separate fixture 38, for example, a bracket. The downstream end 34 d is located away from the upper portion of the pump room cover 37 instead of closely contacting the upper portion of the pump room cover 37. Therefore, the downstream end 34 d of the reducing agent line 34 is positioned above the front intermediate portion 34 b and the rear intermediate portion 34 c.

Hydraulic pumps driven by the engine 22 are arranged inside the pump room. Hydraulic oil in hydraulic oil tank 18 is pressurized by one or more of the hydraulic pumps and supplied to working apparatus 14 to perform useful work. As a result, the temperature of the hydraulic oil returned to the tank 18 becomes high during operation of the machine.

In the reducing agent supply apparatus 31, the liquid reducing agent pump 33 supplies the liquid reducing agent such as urea water in the liquid reducing agent tank 32 in the storage box 16, to the exhaust gas cleaning apparatus 23 in the engine room 19 through the reducing agent line 34, and the injector 29 injects the liquid reducing agent into the pipe 28 a connected to an upstream side of selective catalytic reduction apparatus 28.

Since the liquid reducing agent tank 32 that stores the liquid reducing agent is located away from the engine 22, the liquid reducing agent stored in the liquid reducing agent tank 32 is unlikely to be thermally affected by the engine 22. Furthermore, since the reducing agent line 34 (rear intermediate portion 34 c) is arranged above the level OS of the hydraulic oil O stored in the hydraulic oil tank 18 and along the side surface of hydraulic oil tank 18, the liquid reducing agent flowing through the reducing agent line 34 is unlikely to be thermally affected by the hydraulic oil stored in the hydraulic oil tank 18. Therefore, temperature rise of the liquid reducing agent can be minimized, and the liquid reducing agent can be managed to fall within a specified allowable temperature range using a low-cost structure with no special cooling water conduit or pump.

Since the reducing agent line 34 (rear intermediate portion 34 c) is arranged above the upper surface 18 b of the hydraulic oil tank 18, the reducing agent line 34 (rear intermediate portion 34 c) can be easily and reliably arranged above the level OS of the hydraulic oil O even if when the hydraulic oil tank 18 is filled with the hydraulic oil O. Furthermore, the reducing agent line 34 (rear intermediate portion 34 c) is arranged above the edge of the upper surface portion 18 b of the hydraulic oil tank 18 that is contiguous with the side surface portion 18 a. Thus, the rear intermediate portion 34 c of the reducing agent line 34 is routed laterally away from any heat of the hydraulic oil O which may be conducted directly upward. Consequently, the reducing agent line 34 is unlikely to be thermally affected by the hydraulic oil O.

Moreover, the exhaust gas cleaning apparatus 23 and the liquid reducing agent tank 32 are arranged on the same side of the machine body 11 side by side in the front-rear direction, and the reducing agent line 34 is routed in the front-rear direction along the side surface portion 17 a of the fuel tank 17 and the upper surface portion 18 b of the hydraulic oil tank 18, which are positioned between the exhaust gas cleaning apparatus 23 and the liquid reducing agent tank 32. Thus, the reducing agent line 34 does not need to meander, and can be minimized in length.

Whether the reducing agent line 34 is fixed using the fixtures 35 provided on the hydraulic oil tank 18 or the decorative cover 21, the reducing agent line 34 can be easily fixed with better outer appearance. In particular, when the fixtures 35 are provided on the decorative cover 21, the reducing agent line 34 can be reliably located away from the hydraulic oil tank 18 so that heat from the hydraulic oil O stored in the hydraulic oil tank 18 is even more unlikely to be transmitted to the reducing agent line 34.

The inclusion of the above-described machine body 11 allows provision of an inexpensive configuration that enables effective temperature rise suppression of the liquid reducing agent in the liquid reducing agent tank 32 and in the reducing agent line 34, for a working machine 10.

The reducing agent line 34 described previously is arranged above the upper surface portion 18 b along the edge formed with side surface portion 18 a of the hydraulic oil tank 18. However, the rear intermediate portion 34 c may also be arranged in the space S between the decorative cover 21 and the side surface portion 18 a of the hydraulic oil tank 18, for example, as in the case of another embodiment depicted in FIG. 4 and FIG. 5 as long as the position of the rear intermediate portion 34 c remains above the level OS of the hydraulic oil O. In this case, the reducing agent line 34 may be fixed to the side surface portion 18 a of the hydraulic oil tank 18 using the fixtures 35 or to the inner surface of the decorative cover 21 facing the hydraulic oil tank 18 using the fixtures 35. In this configuration, the rear intermediate portion 34 c of the reducing agent line 34 may be at least partially below upper surface portion 18 b, but remains routed laterally away from the heat of the hydraulic oil O conducted directly upward. Consequently, the reducing agent line 34 is unlikely to be thermally affected by the hydraulic oil O and is prevented from being externally visible. Thus, better machine outer appearance can be kept and the space S between the decorative cover 21 and the side surface portion 18 a of the hydraulic oil tank 18 can be effectively utilized.

If there are tanks other than hydraulic oil tank 18 that store a fluid having high temperatures at least during operation between the liquid reducing agent tank 32 and the exhaust gas cleaning apparatus 23, the reducing agent line 34 may be arranged alternatively or additionally along a side portion of those tanks above the level of the fluid contained therein.

The fixtures may be, for example, bosses provided on the hydraulic oil tank 18 or the decorative cover 21 to hold the reducing agent line 34.

The machine body 11 is applicable to machines other than a working machine as long as the machines are driven by engines, and can be applied to, for example, transportation machines.

INDUSTRIAL APPLICABILITY

The present invention can be utilized by operators involved in, for example, manufacture of machine bodies and working machines characterized in the arrangement structure of an exhaust after-treatment apparatus. 

We claim:
 1. A machine body comprising: an exhaust after-treatment apparatus that executes a reduction treatment on a predetermined oxide in exhaust gas from an engine using a liquid reducing agent; a reducing agent tank provided at a position distant from the engine to store the liquid reducing agent; a working fluid tank positioned between the exhaust after-treatment apparatus and the reducing agent tank to store a working fluid having an high temperature during machine operation; and a reducing agent supply line arranged along the working fluid tank at a position above a level of the fluid stored in the tank to supply the liquid reducing agent from the reducing agent tank to the exhaust after-treatment apparatus.
 2. The machine body according to claim 1, further comprising a decorative cover that covers a side surface portion of the working fluid tank, wherein the reducing agent supply line is arranged in a space formed between the decorative cover and the side surface portion of the tank.
 3. The machine body according to claim 2, wherein the reducing agent supply line is at least partly fixed to a tank side of the decorative cover using a fixture.
 4. The machine body according to claim 3, wherein the reducing agent supply line is at least partly fixed to the tank using a fixture.
 5. The machine body according to claim 1, further comprising: a storage box formed on a front portion of the machine body opposite the exhaust after-treatment apparatus, wherein said reducing agent tank is positioned inside said storage box.
 6. The machine body according to claim 1, wherein the machine body is an upper slewing body of a hydraulic excavator, and said working fluid tank storing a working fluid is a hydraulic oil tank. 